Transparent aluminium is 'new state of
matter'
Experimental set-up at the FLASH laser used to discover the new state of matter.
(PhysOrg.com) -- Oxford scientists have created a transparent form of aluminium by bombarding
the metal with the world’s most powerful soft X-ray laser. 'Transparent aluminium' previously only
existed in science fiction, featuring in the movie Star Trek IV, but the real material is an exotic new
state of matter with implications for planetary science and nuclear fusion.
In this week’s Nature Physics an international team, led by Oxford University scientists, report that a short
pulse from the FLASH laser ‘knocked out’ a core electron from every aluminium atom in a sample without
disrupting the metal’s crystalline structure. This turned the aluminium nearly invisible to extreme
ultraviolet radiation.
''What we have created is a completely new state of matter nobody has seen before,’ said Professor Justin
Wark of Oxford University’s Department of Physics, one of the authors of the paper. ‘Transparent
aluminium is just the start. The physical properties of the matter we are creating are relevant to the
conditions inside large planets, and we also hope that by studying it we can gain a greater understanding of
what is going on during the creation of 'miniature stars' created by high-power laser implosions, which may
one day allow the power of nuclear fusion to be harnessed here on Earth.’
The discovery was made possible with the development of a new source of radiation that is ten billion times
brighter than any synchrotron in the world (such as the UK’s Diamond Light Source). The FLASH laser,
based in Hamburg, Germany, produces extremely brief pulses of soft X-ray light, each of which is more
powerful than the output of a power plant that provides electricity to a whole city.
The Oxford team, along with their international colleagues, focused all this power down into a spot with a
diameter less than a twentieth of the width of a human hair. At such high intensities the aluminium turned
transparent.
Whilst the invisible effect lasted for only an extremely brief period - an estimated 40 femtoseconds - it
demonstrates that such an exotic state of matter can be created using very high power X-ray sources.
Professor Wark added: ‘What is particularly remarkable about our experiment is that we have turned
ordinary aluminium into this exotic new material in a single step by using this very powerful laser. For a
brief period the sample looks and behaves in every way like a new form of matter. In certain respects, the
"Transparent aluminium is 'new state of matter'." PHYSorg.com. 27 Jul 2009. http://www.physorg.com/news167925273.html
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way it reacts is as though we had changed every aluminium atom into silicon: it’s almost as surprising as
finding that you can turn lead into gold with light!’
The researchers believe that the new approach is an ideal way to create and study such exotic states of
matter and will lead to further work relevant to areas as diverse as planetary science, astrophysics and
nuclear fusion power.
A report of the research, 'Turning solid aluminium transparent by intense soft X-ray photoionization', is
published in Nature Physics. The research was carried out by an international team led by Oxford
University scientists Professor Justin Wark, Dr Bob Nagler, Dr Gianluca Gregori, William Murphy, Sam
Vinko and Thomas Whitcher.
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"Transparent aluminium is 'new state of matter'." PHYSorg.com. 27 Jul 2009. http://www.physorg.com/news167925273.html
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